Method of constucting wearing surfaces of roads and the like



Patented Get. 23, 19%.

sari EVERETT FINLEY, OF ATLANTA, GEORGIA.

METHOD OF CONSTRUCTING WEARING SURFACES OF ROADS AND THE H0 Drawing. Application filed July 28,-

- The purpose of this invention is to manufacture in place on the roadway a bituminous wearing surface for various types of foundations; These foundations may include old j pavements of concrete, block, brick, asphalt,

etc, or such waterbound types as macadam, gravel, top-soil, sand-clay, shell, etc. The novelty of the invention lies in the newf'and valuable result obtained by the use of a combination of old and new methods of manufacture; in brief, I manufacture, preferably by cold-mix methods, a bituminous wearing surface for roads, streets, etc., which will approximate the strength and durability of bituminous wearing surfaces manufactured by hot-mix methods. Further,- my cold-mix wearing surface will be welded and blended with the foundation into a bond far superior to any bond attainable with hot-mix surfaces. I

Old foundations may be leveled up to proper cross-section either by filling depressions by approved methods,or by scarifymg, reshaping andrecompacting. If no curb'is presentthe margin. of the area to be surfaced requires extra strength or water-resistance. I remedy this defect by the use of an inverted curb with an extra quantity of asphaltic cement,'as explained in my Patents Nos. 1,462,903 and 1,544,440. This stable asphalt maybe applied simultaneously with or just in advance of the application of bitumen named above.

Upon thefoundation so prepared I apply a bitumen which has been refined and blended to meet the requirements of the foundation in question. Due to the fact that the bitumen will flow more readily over wetted surfaces and its penetration into the upper surface of certain types of aggregates used in the construction thereof, than it will over the same surface when dry, I sprinkle such surfaces with water prior to the application of the bitumen. The further advantage of such sprinkling is explained in my Patent No. 1,462,902. The function of the'bitumen so applied is four-fold: First, to penetrate as deeply as possible into porous material in contact with it and replace the unstable water-bond with a stable asphalt-bond; seo 0nd, to enliven the bitumen in old bituminous foundations; third, to bond the mortar course of the wearing surface firmly to the foundation; fourth. through the diffusion and dissipation of its more volatile and 1926. Serial No. 125,594.

,asphaltic cement, either straight or distilled,

or dissolved in quick drying na tha.

Upon the bitumen so applled I cast a rock detritus or mineral aggregate. This material may be screenings, mine tailings,

clay, sand-clay, top-soil, or other mixtures of inorganic matter containing finely divided matter capable of capillary action. Later applications of bitumen and detritus may he added to remedy deficiencies in. earlier applications or to increase the thickness of the wearing surface. The bitumen upon contact with this rock detritus diffuses through such material aided by capillarity, surface tension, pressure, traiiic, heat of sun, etc. If left to traffic and climate to cause this diffusion and the ultimate dissipation of more volatile matter, much of the rock detritus is wasted in dust before maturity is attained.- This dust in not only a nuisance, but it is a direct loss of useful material, and the long wait for the elements and traflic to accomplish this maturing often runs into many months.

In some instances it may be desired to 0 en the roadway to traffic and exposure to t e elements to bring about this diffusion and the ultimate dissipation of the more volatile matter, to bring the bituminous mortar to the desired consistency, this to besubsequently followed with a casting of stone chips, pea gravel or other suitable material, or a subsequent application of bituminous cement, preferably after the above, can be greatly accelerated and the maturing process more quickly brought about by converting material formerly wasted in dust into a valuable wearing surface. This artificial maturing of the mortar is accomplished by kneading and mixing,preferably with my traffic tread roller, as fully described in my Patent No. 1,637,993, dated August 2, 1927. In connection therewith, there may also be used a direct application of artificial heat and pressure, and also by stirring the loose detritus in the presence of artificial heat, or by combination of these means.

By forming and maturing this bituminous mortar or concrete in the manner stated, where two or more grains of finel divided matter adhere, such as top-soil, c a dust, or the like are used, the particles are thus separated, and in some instances single ains crushed, increasing the percentage of nes and therefore the stability of the bituminous mortar or wearing surface.

In the event that the character of the' correspondtotliefiller or mineral dust addedto sheet asphalt, or it may correspond to the coarse aggregate in asphaltic concrete. In the latter case, where the mortar can be markedly improved by reinforcement with coarse rock detritus such as stone chips, pea gravel, etc., I apply this material to the surface of the mortar before the diffusion and volatilization is far advanced, so' that .the

- mortar will still be sticky, and will readily wet and adhere to such material. I then knead this material intothe mortar, increasin the reinforcement u'ntilthe desired stabifity is attained, and the foundation is completely protected.

I would sum up the above method as follows: I prepare suitable foundations to receive a wearing course of mortar. ,I build thereon and bond thereto a mortar of rock detritus and bitumen, manufactured in situ and preferably by the cold-mix process, having such characteristics that it will toughen and become stron or under traffic and climatic influences; accelerate this maturing process by artificial means; and I further stren then and reinforce this mortar by knea ing into it the required material until, 4

after completion, a wearing surface is producedwhich will approximate the strength and durability of a hot-mix surface.

In claiming novelt for this method I realize that the following methods are old in the art:

1. To ap 1y a prime coat and then 'cover with rock dbtritus.

2. To apply a prime coat, follow with heavier bitumen, and then cover with rock detritus.

3. To depend on both slow and rapid diffusion of volatile hydrocarbons to increase the stren th of the layer.

4. To uild up asurface treatment by layers through alternate applications of bitumen and mineral matter.

5. To depend on trafiic and sun heat to mature the surface.

All of the above may be utilized in my new method, but none of them cover the novel features named because none of them produce a mortar bonded deeply and thoroughly to the foundation and capable of attaining high ultimate strength through slow maturing, and then by artificial means rapidly maturing that mortar while, at the same time, adding largel to its strength through the process of kneading into -it finely divided matter to act as filler, as well as coarse aggregate to add reinforcement.

Likewise, it 1s old to the art to apply a layer or coarse aggregate in bituminous macadam surfacing of stone that ranges from 2 to in size, and then apply a coating of as haltic cement and cover with clean stone 0 ips or pea gravel that would range in s1ze from 4 to also 1n surface treatments it is old to apply ala-yer of liquid or semi-liquid or a bituminous cement and cast stone or pea gravel from 1" to ,4 in size, and over this coarse aggregate to make a second application of asphaltic cement and cover with fine material such as stone dust, sand and the like; or there may be sufficient bituminous material applied in the first instance and then covered with the size stone or gravel above named suflicient to not require a second coat or bituminous cement, and then cover with the finely divided matter or material, as above stated.

Any of the practices above named are distinctly different from the instant invention, as it will be noted that I first use the line material to cover the bituminous cement to build u the bituminous mortar, very dense in COIISISlZBIICy, so that when the coarse a gregate, or a casting or kneading of add1- tional fine material is applied, the dense bituminous mortar is worked upward and the additional material downward, producing a bituminous wearing surface of high stability.

Under the method as above described, it

is not possible to overload the bituminous cement and .weaken its strength b the addition of too much aggregate, as t e nature I of the materials thus used and from the mannerin which they are handled-and brought to a state of maturity, will cause them in every instance to refuse a surplus of covering material.

What I claim is:

1. The method of constructing and applying wearing surfaces to road structures which comprises covering the structure with Y bitumen of suitable consistency, adding to the bitumen coating mineral aggregate of varying sizes, and kneading and thoroughly admixing the bitumen and aggregate to ma ture the composite surface coating and unite v the same With the original road structure.

3. The'method of constructing and applying Wearing surfaces to road structures which comprises covering the structure with bitumen of suitable consistency, adding to the bitumen coating fine mineral aggregate, kneading and thoroughly admixing the bitumen and aggregate in situ, adding coarser aggregate, and continuing the kneading and admixing until the coating is substantially homogeneous.

4. The method of constructing and applying Wearing surfaces to road structures which comprises Wetting the surface of the road structure, covering the wetted surface with bitumen of'suitable consistency, adding to the bitumen coatingmineral aggregate,

and kneading and thoroughly admixing the bitumen and aggregate to mature the compos ite surface coating and unite the same with the original road structure.

In testimony whereof I afix my signature.

- SAM EVERETT FINL'EY. 

